3.5 Microbial composition turnover among regions and host
plants
Microbiome composition comparisons between the putative native South
Africa and introduced range of medfly were only statistically
significant for the pairwise comparisons with Spain (F =
6.4, R2 = 0.30, p = 0.015), Colombia (F =
7.4, R2 = 0.26, p = 0.015) and Brazil (F =
7.8, R2 = 0.41, p = 0.015). In the introduced range, the
microbiome structure of Spain was significantly different to that of
Israel (F = 3.6, R2 = 0.15, p = 0.015) despite
being collected partly on the same host plant (Fig. 1) and to Brazil
(F = 6.3, R2 = 0.28, p = 0.015). Conversely, the
microbial communities from Spain, Australia and Colombia showed no
significant differences despite their geographic distances and being
collected from different host plants. In the neotropical region, the
microbiome of medflies from Brazil and Colombia showed significant
differences (F = 7.0, R2 = 0.24, p = 0.015),
although collected from different host plants (Fig. 1). ANOSIM analysis
at the global scale showed significant differences in samples collected
from different locations (R = 0.429, p = 0.001) and
different host plants (R = 0.196, p = 0.001),
demonstrating the greater importance of geographical distance for
microbiome composition compared to diet.
Exclusively for the sampling sites whose microbiome composition was
significantly different to South Africa in the pairwise comparisons, we
performed differential abundance analyses on the most abundant ASVs to
identify the differences at the genus taxonomic level. The comparisons
between South Africa and Spain did not detect any significant changes
with the threshold implemented (FDR < 0.01). Indeed, the
genus Klebsiella was the only altered in high abundance between
South African and Colombian samples, while 48 bacterial ASVs were
evidently different in the analysis between Brazil and South Africa
sampling sites (Fig. 8). Worth mentioning is that samples from both
localities were collected in guava and presented a similar relative
abundance in the genus Flavobacterium. The
genus Gluconobacter and unclassified Halomonadaceae were detected
only at the low relative abundance in all medfly samples collected in
South Africa. In contrast, a high abundance of
genus Acinetobacter , unclassified Burkholderiaceae, unclassified
Clostridiales, Dysgonomonas and Escherichia-Shigella, was
harboured exclusively across all the medfly samples collected in Brazil
(Fig. 8).